The present invention relates to an improved apparatus for cleaning, drying and testing for oil content in air generated from compressors or other sources of flow and delivered through a delivery system where there is a need or desire to remove oil, particulate matter or water droplets and or humidity from a gas stream.
In the railroad industry, the owners and operators of locomotive and other railroad equipment require or find it operationally desirable to remove as much water vapor, oil, humidity and particulate matter from compressed air as possible, when such air is used to charge and operate the air brake system of the equipment. Additionally, it is desirable to be able to measure the oil content that contaminated the gas stream in order to determine proper maintenance of the compressors and extend the life of air brake equipment of locomotives and cars.
Many railroads utilize dryers and after coolers on their locomotives and yard compressors. For the most part, these dryers and after coolers are very efficient in removing the humidity generated from the process of compressing air; however, they do little to protect the system from oil contamination. Moreover, the presence of oil, will destroy the desiccant's ability to adsorb water vapor. A properly maintained locomotive dryer system with an effective and clean desiccant, is particularly efficient because the system generates air that has been cleaned and dehumidified and deposited directly into the equipment train line through air hose couplings directly between the locomotive air system and each adjoining car.
The yard compressors present a different and unique problem. The yard compressors generate compressed air that, in most instances, is dehumidified with a similar air dryer. The dry air is then delivered to a series of outlets that are located at the head or rear location of various tracks by means of an underground piping system. This piping can be thousands of feet long before reaching the outlet ports for delivery to the train line. This piping is, in many instances, made of steel threaded together with couplings. Subsequently, any breach or loosening of the pipe or couplings will allow groundwater and particulate matter to enter the pipe, thus contaminating the airflow. Even though the air may be dry as it leaves the central compressor, as a practical matter is it virtually impossible to prevent moisture from entering the compressed air through leaks in the piping system between the point of generation and the point of use. Whether this moisture is present in the form of humidity or condenses to liquid water, it is detrimental to the ultimate use. Rust can also be created when these factors are present causing additional problems. Additionally, because the piping is usually below ground surface level, the temperature is significantly below the ambient temperature of the compressed air when it leaves the compressor. A dryer which uses a desiccant for example may reduce the moisture content level to withstand a dew point depression of 20 degrees below ambient. This means that if the air is cooled 20 degrees below its ambient temperature after leaving of the dryer, it will begin to condense and form water droplets. This underground piping system used to deliver air to cars and locomotives is almost universally used in the railroad industry and proves effective means of delivering air to pre-charge trains and cars. It eliminates the time that might otherwise be needed to charge a train line using a locomotive compressor only. However, because of leakage, rust, groundwater and excessive cooling of the air that occurs as a result of the air delivery piping running for hundreds and sometimes thousands of feet under the ground from the compressor, the dryers used on yard compressors at the source are not effective and cannot prevent water seepage into the delivery line. Moreover, if excessive cooling occurs, the dryer is not effective in keeping moisture from entering the train's brake system unless moisture is removed to the point significantly below the ambient moisture level at the source. This is not always possible. Short of removing the compressor to a closer location or replacing old leaking underground piping, there is no practical effective device which is in use to address this problem.
The seriousness of contaminants entering the air brake system cannot be overstated. The presence of oil, rust, particulate matter and excessive moisture cost the U.S. railroad industry up to in excess of $50 to $60 million a year in clean oil test and stencil (CO T. & S.) cost alone. U.S. federal regulations mandate the railroad industry to change out Passenger Locomotive air valves on a 36 month preventative maintenance plan. On the freight side, there are approximately 30,000 locomotives in the United States at an estimated cost of $5000 to $6000 per locomotive this equates to $150 to $180 million. This cost does include all of the other remedial costs associated with this maintenance regulation.
The contaminant problem and the lack of a cost-effective means to address it is a significant factor in the 36 month time interval mandated for CO T.& S. If the industry were able to address this issue by monitoring and reducing the contaminants levels entering into the brake system, the cost would be significantly reduced by providing a longer life expectancy for the air brake valves and justification for increasing the CO T.& S. time interval.
The present invention also relates to an improved apparatus and method for the testing of oil content in a gas stream generated by compressors and has application to the railroad, commuter and trucking industries. For example, in the railroad industry the owners and operators of railroad equipment use compressors to generate air pressure to operate their brake systems. This type of air brake system is also used in the commuter and trucking industries. Many of these compressors utilize air dryers which use a desiccant type filter to remove humidity from the air. If the humidity is not removed from the air, the vapor can condense into water. Additionally, the brake valves which are used to operate the brake system have rubber components that are adversely affected and react to the presence of oil, water and/or other contaminants. The industry has long sought an efficient and cost effective means to monitor the oil content in the compressed air. The presence of oil in the air will reduce the life expectancy of valves and other components, as well as the desiccants which are used to dry the air. Additionally, the presence of oil in the air is an indication that the compressor rings are worn or broken allowing oil lubricants to leak into the air supply.
In the railroad industry, as well as in the trucking industry, current methods to detect oil are costly and time-consuming. These methods can require costly modifications to the equipment to attach monitoring devices or idle equipment for extended periods of time while the tests are performed.
Federal regulations relating to air pressure of train lines in the railroad industry are governed by regulations under part 49 CFR 232 and 49 CFR 238 (freight and passenger). FTA safety regulations are covered under 49 CFR 659.31 and reference the manual for development of rail transit safety program plans (A. P. T. A.) Aug. 20, 1999. The Federal regulations relating to the trains air brake pressure requires that the train line may not exceed a 5 pound leak during the test for initial terminal brake. Alternatively, Federal regulations also allows an alternative method of testing that is referred to in the industry as the “air flow method”. Use of this method allows up to 60 cubic feet per minute of leakage.